U.S. Pat. No. 8,833,626B2 discloses an actuation device of a fastening tool. Referring to FIGS. 3 to 5 of the U.S. patent, the actuation device mainly includes a contact trip assembly 130 of a movable nose 150 connected to a nose assembly 22, a trigger assembly 110 including a trigger 112, and a check pawl 116. The contact trip assembly 130 includes a lower contact arm 132 connected to the movable nose 150, and an upper contact arm 134 connected to the contact arm 132 and being formed with an opening 140.
By changing the operation sequence of the contact trip assembly 130 and the trigger 112, the fastening tool can be operated in a sequential striking mode (see FIGS. 5 to 10 of the U.S. patent), where, after a single strike, the check pawl 116 engages the opening 140 of the opening 140 upper contact arm 134 to avoid further strike, or a repetitive striking mode (see FIGS. 11 to 14 of the U.S. patent), where multiple strikes are allowed.
During manufacturing of the abovementioned actuation device, the contact trip assembly 130 needs to be processed to form the opening 140, and the check pawl 116 needs to be formed with a protrusion for engagement with the opening 140, thereby increasing the complexity of the structure and manufacturing difficulty. Moreover, the check pawl 116 and the opening 140 may not be properly aligned during operation.